The present invention relates generally to optical waveguides, and, more specifically, to optical panels formed therefrom.
U.S. Pat. No. 5,381,502 discloses a thin optical panel having optical waveguides stacked together in laminated sheets. Each waveguide includes a central optical core bound between cladding layers. The cladding has an index of refraction less than that of the core for effecting total internal reflection as light is transmitted through the core.
The waveguides have opposite ends which define a respective inlet face for receiving projected light, and an outlet face or screen for displaying the light in any suitable form such as a video image. In an exemplary embodiment, the waveguides are beveled at their outlet ends at a small acute angle of up to a few degrees, and their inlet ends are coplanar with each other to position the inlet face obliquely or generally perpendicular to the screen.
The waveguides extend the full width of the screen, and the height of the screen corresponds with the total number of laminated waveguides. The screen may be exceptionally thin on the order of one or two centimeters, with a multitude of waveguides of corresponding thinness being used. For example, 525 waveguides may be laminated together for effecting 525 vertical lines of resolution for use in projecting a television image.
In this construction, the individual waveguide cores are extremely thin, on the order of about 50 microns, for example. The cores are made of an optically transmissive material such as glass or plastic acrylics or polycarbonates. In thin sheets the individual cores are relatively flexible in bending while still retaining lateral rigidity and brittleness in the planes of the sheets.
However, the multiple cores are laminated together with the cladding therebetween, typically in the form of a suitable adhesive such as epoxy. Once the multiple cores are laminated together in this manner, they are bonded to each other and become quite rigid in their bending direction across the laminations. The laminated panel is therefore rigid not only laterally along the longitudinal and transverse directions in the planes of the individual cores, but is also rigid orthogonally thereto across the section of the laminated waveguides. The optical panel thusly has structural rigidity and integrity, and is self supporting when mounted in a suitable housing or cabinet, or when mounted on a wall, for example.
A particular advantage of this form of laminated optical panel is its unlimited size potential. Such panels may be made from small size to exceptionally large size by simply controlling the size of the individual waveguides themselves.
In large size, the practicality of transportation thereof becomes a problem. For large, portable optical panels, the rigid construction of the laminated waveguides substantially increases the difficulty of packaging, handling, and transportation, as well as requiring a large space for the storage of the panel when not in use.
Accordingly, it is desired to provide a compact, portable optical panel irrespective of the large size thereof.